SKIMMED-MILK DEMINERALIZATION BY ELECTRODIALYSIS - CONVENTIONAL VERSUS SELECTIVE MEMBRANES

Electrodialysis (ED) is a membrane technique that is useful in the demineralization of dairy products. In this work, experimental results obtained in batch electrodialysis of skimmed milk are presented. Two kinds of membranes were used: the first kind were conventional membranes in PVC and the second were monovalent ion selective membranes which are now available on the market. This latter type of membrane permits the transport of monovalent ions but limits the passage of large ions which have a high valency. The limiting current was measured as a function of feed flow into the stack. The results obtained when using both types of membranes were compared for elimination rate of K+, Na+, Cl-, Ca2+, Mg2+ and PO43- ions as well as for current efficiency and electric power consumption in the separation process.